Generally, such rotating portions are sealed by use of a ring-like shaped sealing member formed of flexible material and mounted on the stationary or rotary member, so that the sealing member closes a gap between the stationary member and the rotary member, thereby preventing dust or rain water from entering the bearings.
The sealing member in such a construction, however, contacts at its inner periphery or outer periphery with the rotary member or stationary member to close the gap. However, the sealing is incomplete and exhibits a large frictional resistance. As a result, not only is the rotary member hindered from smooth and light rotation but also wear of the sealing member occurs requiring a renewal of the sealing member in a short time.